From DE 10 2007 033 611 A1 an exhaust heat utilisation device is known. This comprises an exhaust heat utilisation circuit, in which a working medium circulates. In the flow direction of the working medium, an evaporator for evaporating the working medium, which can be supplied with waste gas of the combustion engine, an expansion machine for expanding the working medium, a condenser for condensing the working medium and a delivery device for driving the working medium are arranged one after the other in the exhaust heat utilisation circuit. In addition, a heat storage unit, which is incorporated in an exhaust gas path leading to the evaporator, is provided with the known exhaust heat utilisation device. With the help of a valve device, the exhaust gas flow can be divided over the heat storage unit and over the evaporator dependent on a value representing the available heat energy of the exhaust gas. For example, the evaporator is supplied with exhaust gas as a matter of principle. If more exhaust gas heat is available than is required for the evaporation, an exhaust gas part flow can be fed to the heat storage unit. If, by contrast, less exhaust gas heat is available than required for the evaporation and if the temperature of the heat storage unit is higher than the temperature of the exhaust gas, the exhaust gas flow can be initially conducted through the heat storage unit and subsequently to the evaporator. With the known exhaust heat utilisation device, a heat storage unit incorporated in the exhaust system of the combustion engine is thus used for pre-heating the exhaust gas as a function of demand.
The present invention deals with the problem of stating an improved or at least another embodiment for an exhaust heat utilisation device of the type mentioned at the outset, which is characterized in particular by a practical value or by an additional functionality of the exhaust heat utilisation circuit. Additionally or alternatively, the energetic efficiency of the combustion engine equipped with the exhaust heat utilisation device is to be increased.